One of the objects of the present invention is a method of reconditioning pipes and conduits such as, for example, sewage mains, pipelines, ducts, water mains, gas mains, tunnels or the like, hereinafter referred to collectively as "conduits, " by lining the inner walls thereof with a tube made of fabric impregnated with a hardenable resin.
Methods of lining of this type are known in the art.
All these known prior art methods have the disadvantage that, due to any unevenness in the wall of a conduit to be reconditioned, or due to curves or drain-traps along the extend of the conduit, the application of the fabric tube is difficult.
A further object of the present invention is a method for the construction of new pipes and conduits, such as for instance underwater, underground or surface conduits and pipelines, by the expansion of a tubular impermeable sheath, and the concurrent lining of the external surface of said sheath by winding on it a fabric or a continuous glass fibers layer impregnated with a hardenable resin.
At the present time, pre-formed pipe sections are used to construct the conduits and the pipe sections which are assembled together during the laying operation. Alternatively, extruded pipes can be used to construct the conduits.
The above prior art methods have the disadvantage, particularly with respect to the construction of underwater pipelines and conduits, that they are easily subject to the danger of failures, which could occur during the launch, especially on occasion of consistent sea waves.
The present invention aims to obviate to the above and other disadvantages of the prior art methods, by providing a monolithic pipeline, exempt from joints and, as the underwater pipelines are concerned, from the danger of failures due to the sea waves.
According to a characteristic of the present invention, an impervious sheath of PVC or the like material, is wound on his external surface with a lining formed by a fabric and/or by continuous fibers of glass or other suitable materials, impregnated with a hardening resin. Inside of said sheath at least one expander member is inserted, which expander is formed by a tubular ring of cylindrical shape, of resilient, flexible impervious material, which is pressurized so as to cause a fluid-tight engagement of the surfaces of its inner axial bore. Thereafter a pressure is exerted by means of a pressurized fluid against one side of said expander, whereby the latter is caused to advance along the opposite side of the conduit with a rotary-traslatory motion like a cylindrical crawler track, thus exerting a uniform and homogeneous pressure against the walls of the pipeline forming sheath.
The force whereby the expander presses the tube impregnated with hardenable resin may be varied by adjusting the inflating pressure of the expander.